LAS VEGAS — In a room just off the lobby of the MGM Grand Hotel this week, boxer Floyd Mayweather Jr. eased back on a couch and prepared to talk to a large cluster of sportswriters. An assistant handed him a tall coffee, and Mayweather, a true sweet scientist, stirred in half a dozen packets of sugar.

Mayweather undeniably leads la dolce vita. He brings his 45-0 record into Saturday night's pay-per-view welterweight fight against Marcos Maidana as the world's highest-paid athlete. Mayweather is on track to earn about $90 million this year. His life of luxury affords him a fleet of absurdly expensive sports cars, a vault of bling (a recent addition: an emerald-encrusted Rolex valued at $400,000), a 22,000-square-foot Las Vegas mansion, and enough left over to say that he wants to buy a chunk of the Clippers.

"I'm very, very comfortable," said Mayweather, 37, who conceded the most difficult part of his day is picking out which car he wants to drive to his workouts. "I go out in the garage — I go out in the garages — and I look around and say, 'Do I want to drive you, you, you or you?' Then I go to the other side and say, 'Do I want to drive you, you…?' "

That brings up the question: Where is the motivation to keep boxing? What fuels the hunger for someone widely regarded as the best pound-for-pound fighter in the sport, a 10-time world champion in five weight divisions?

"The legacy," said Mayweather, who is on the third fight of a six-fight deal he signed with Showtime. "When you mention boxing, all I want you to mention is one man, and that's Floyd Mayweather. When my career's over, I don't want y'all talking about nobody else."

But Mayweather's critics insist that for the last five years he's been running from Manny Pacquiao, unwilling to fight the rapid-punching Filipino superstar. There were early hurdles. Mayweather wanted a drug-testing program that Pacquiao initially refused but eventually agreed to. They argued over how to split the purse, but Pacquiao has since conceded to a smaller percentage. And then there's the bitter feud between Pacquiao's promoter, Top Rank Chairman Bob Arum, and the man who has promoted all of Mayweather's fights since 2007, Golden Boy Promotions Chief Executive Richard Schaefer. Arum and Schaefer have not co-promoted a fight since 2009.

The years of waiting have taken the luster off a Mayweather-Pacquiao fight, because Pacquiao lost two fights in 2012.

"I had my ups and downs with Arum," Schaefer said. "I've tried many times to let the past be the past and move on, and somehow reach out and find a way that we can work together again. We've done it a couple of times, but every time it just ended up in disaster.

"Mayweather made it clear: If Pacquiao wants to fight him, he should leave his promoter, Bob Arum. And I feel the same way."

At the moment, the focus is on Maidana (35-3, 31 knockouts), a hard-punching Argentine who slugged his way into Saturday's fight with a victory last December over Adrien Broner, who some regarded as a possible up-and-coming Mayweather. Maidana knocked him down twice to claim an easy decision.

Maidana, an 11-to-1 underdog, showed up at the pre-fight news conference this week wearing sunglasses and a black tuxedo with faint silver polka dots.

"Mayweather is an excellent fighter," he said, through an interpreter. "But I don't give a … about him."

Clearly, there are lots of people who do care about Mayweather, or at least care enough to follow him on social media. He has 4.7 million followers on Twitter, behind only LeBron James, Kevin Durant and Dwight Howard among active U.S. athletes in the four major professional sports.

Mayweather is the focus of Showtime's "All Access," a half-hour weekly show that gives viewers a behind-the-scenes glimpse of his preparation for a fight, as well as his extravagant lifestyle.

"As we've gotten into the couple weeks before the fight, we'll shoot seven days a week," said Stephen Espinoza, executive vice president of Showtime Sports. "Floyd's nocturnal. So we'll start shooting when he goes to the gym around 3 or 4 [p.m.], and then we may be with him all the way until 6 a.m. Because he'll go home, have dinner, maybe go out and have some fun, and then go for a six-mile jog at 4 in the morning. So there's really not a dull moment."

Mayweather, who said he's mulling retirement, possibly even after this fight, is a physical marvel who appears to be at the top of his game when he should be showing signs of age.

"Ten years ago, I thought I had to jog every day," he said. "I'd run miles and miles. Whereas now that I'm older I can let my body rest a day or two. I don't have to come to the gym and spar every day. Just growing and maturing, that's what it's about."

Mayweather said he watches replays of his fights on mute because he's tired of hearing critical commentary.

"A lot of the time, I'm fighting the media, fighting the critics, fighting the jealousy," he said. "I'm fighting a little bit of everything. My whole life has been a fight and a struggle. But I always know how to rise to the top because I'm a natural-born fighter, a natural-born winner at whatever I do."

As for those who criticize him for who he has yet to fight — presumably Pacquiao — the sweet scientist doesn't sugarcoat that.

"A lot of times you hear people say, 'Is Mayweather just protecting his record?' " he said. "The thing is, when I fight a fighter is when I fight a fighter. We fight who we fight. I don't think I'm going to get the props that I truly deserve until my career is over."